Abstract

Using rigorous electromagnetic diffraction theory, we evaluate the potential performance and the limitations of coding diffractive optical elements in the form of a pulse-frequency-modulated carrier grating. This coding scheme employs the first diffraction order of an ultrahigh-frequency binary carrier grating, with a period below 1.5 wavelengths. We establish that the pulse-frequency-modulation structure can be designed with the standard synthesis techniques based on paraxial scalar diffraction theory. However, we had to optimize the groove depth, the aspect ratio, and the carrier period with rigorous electromagnetic theory to achieve close to 100% efficiency and the desired polarization properties. Our method is compared with another recent coding scheme that utilizes the zeroth order of a subwavelength-period pulse-width-modulated binary carrier grating.

© 1994 Optical Society of America

Eigenmode method for electromagnetic synthesis of diffractive elements with three-dimensional profiles

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